DOW JONES NEWSWIRES 
 

Gilead Sciences Inc. (GILD) said it is reviewing a notice letter and has 45 days to file a patent infringement lawsuit against Teva Pharmaceutical Industries Ltd. (TEVA), following Teva's submission to manufacture and market a generic version of HIV drug Atripla.

The potential lawsuit wouldn't be the first time the drug companies have spared over HIV and AIDS drugs. Gilead, a leading maker of AIDS treatments, sued Teva in December to prevent it from making a generic version of HIV drug Truvada until 2021. Teva was seeking U.S. Food and Drug Administration approval to sell a copy of the drug, Gilead's biggest product.

In 2008, Gilead reported Truvada sales increased 33% to $2.11 billion. Atripla sales, meanwhile, rose 74% to $1.57 billion during the year.

In its latest submission on Monday, Teva entered an Abbreviated New Drug Application to the FDA to make a generic version of Atripla, which is currently sold in the U.S. through a joint-venture between Gilead and Bristol-Myers Squibb Co. (BMY).

Teva alleges two of the patents licensed to Gilead are invalid, unenforceable and wouldn't be infringed by Teva's manufacture, use or sale of the product described in its latest submission.

Gilead, meanwhile, said Atripla is protected by 15 patents and said all 15 would need to be invalidated or expire before a generic version of the drug could be marketed.

Last year, Teva challenged the validity of the same two patents in its generic drug application for Truvada. The lawsuit in that case is still ongoing.

Shares of Gilead were down 1.2% at $47.81 in after-hours trading, while Teva's American Depositary Shares were even at $45.49.

-By John Kell, Dow Jones Newswires; 201-938-5285; john.kell@dowjones.com